Apparatus for measuring and adjusting the spring pressure on commutator brushes



Oct. 2l, 1952 M. cuLKosKY 2,614,421

FOR MEASURING A APPARATUS ADJUSTING THE SPRING PRESSURE COMMU TORBRUSHES Filed Patented Oct. 21, 1952 APPARATUS FORMEASURING AND ADJUS'r-ING THE SPRING PRESSURE oNCoMMU- 'raros BRUSHES Mart-in Culkosky, Gary,Ind. Application June 23, 1948, Serial No.y 34,628 f y This inventionrelates to apparatus for adjusting and measuring the spring pressure oncommutator brushes and is a continuation-impart of my copendingapplication, Serial No. 625,577, filed October 30, 1945, now Patent No.2,471,480, patented May 31, 1949.

The amount of pressure by which brushes, such as shown in my copendingapplication, are held in contact with the commutator is very important.In order to avoid unequal distribution of current among the differentbrushes on the machine, it is necessary that the pressure be equal onall brushes.y There is also a limited range of pressure within whichbest brush performance is obtained. If the pressure is too light,imperfect contact with the commutator is liable to result, causingsparking, injury to the commutator surface and undue brush wear.Excessive brush pressure results in unnecessary friction, needless wearand may even reduce the stability of the p brush position in its holderand against the commutator.

It is therefore an object of my invention to provide apparatus foradjusting and measuring the spring pressure on all brushes so that thebrush pressure on the slip ring or commutator can be uniform. i

This and other objects will be more apparent after referring to thefollowing specification and attached drawings, in which:

Figure 1 is a side elevation, partly in section, of my device; and

Figure 2 is a top plan view of Figure l.

Referring more particularly to the drawings, the reference numeral 2indicates an insulated brush holder support mounted on the motor frame(not shown). Attached to the support 2 by means of the bolts 4 is abrush holder 6. The holder 6 has an elongated body member 8 with a pairof spaced apart brush receiving openings l therein. Between the openingsI0 is a pair of spaced apart lugs I2 for receiving a hub I4 which isheld in place by means of screw I6. The hub I4 is provided with tappedholes Il for receiving screws I8 which hold a brush arm 20 in place overthe openings I0. A tap 22 on each end of the arm extends toward theadjacent opening l0. Located in each of the openings l0 is a brush 24having a circular inner portion 26 for bearing against the slip ring 28.A recess 30 is provided in the center of each brush on the side facingthe tap 22. A button-head base 32 having a reduced portion 34 extendingtoward the tap 22 is located in the opening 30. or any other suitabledielectric material. The tap 3 claims. (ci. 7a4-161)" The base 32 ismade of fiber f .e 2 22 is centrally locatedr 'over the base 32' and aspring 36 surrounds the tap and reduced portion 34 of the base. The base32v in addition to insulating the spring from the brush assures a firmeven contact between the brush 24 and the spring' 36; With -thisconstruction the brush 24 contacts the ringj28 throughout the surface 26and no air gap is formed. Wires 38 are connected to the brush in thelusual manner and are fastened to the body member 8rby means of a screw40. `A feed `line 42 is connected to the body member 8 )by means of aScre`w44. i I

The apparatus so far described is that shown'in my above mentionedcopending application.

According to the present invention, at least one of each pair of basesassociated with each brush arm 20 is provided with a tapped opening 46.In that portion of the arm 20 directly above the base 32 is a threadedopening 48 for receiving an acljusting Screw 50 having the tap 22mounted thereon. A lock nut 52 is provided for locking the adjustingscrew in position. The adjusting screw 50 is provided with an axialopening 54. An I- screw 56 passes through the opening 54 and is threadedinto the opening 46. A spring gauge 58 is provided with a hook 68 whichis received in the eye of the bolt 56.

The method of adjusting the brush pressure is as follows:

The I-bolt 56 is threaded into the opening 46 and the spring gauge 58 isattached thereto as shown. A pull is then exerted on the spring gauge 58until the spring 36 is compressed and the base 32 is removed slightlyfrom its seat. Since the spring 36 and spring gauge 58 oppose eachother, the spring 36 will be carrying the same load as the spring gauge58. Since the lever arm between the pivot point I6 and the center ofeach of the pairs of brushes is equal, the pressure on each spring 36will be equal. In this manner the pressure on each of the springs 36 isdetermined. When it is desired to adjust spring pressure to a. certainamount, as for example, 2 pounds, the adjusting screw 50 is turned toincrease or decrease the pressure on the spring 36 until the pressure ongauge 58 will read 2 pounds when the base 32 is just removed from itsseat. In this manner the spring pressure on each pair of brushes 24 isadjusted to the desired amount by making one adjustment. This process isrepeated for each pair of brushes until all the brush pressures areuniform.

In some instances the brushes are not arranged in pairs, as shown, buteach brush has its own individual brush arm. In such a case the brush 1.Measuring apparatus for use with a motor' brush holder having a bodymember with a brush receiving opening therein, a brush in said opening,a brush arm attached to said body member and extending over saidopening, a base bearing against said brush, said base having an axialthreaded opening therein, said arm having a threaded openingtherethrough in axial alignment with the first named axial opening, abushy ing in said second named opening, said bushing having an axialopening therethrough, and a spring extending between said base and saidbushing; which apparatus comprises a bolt extending through the bushinginto the threaded opening in the base, and a tension indicating means-fastened to the free end of said bolt.

' 2. Apparatus of the kind described comprising a commutator brushbearing against the slip ring of 'a motor, a brush arm, a bushingadjustably mounted'in said brush arm in alignment with said brush, abase bearing against the brush, said base having an axial threadedopening therein, a spring extending between said bushing and said base,the bushing being formed with an axial opening whereby a bolt may besecured in the threaded opening and a tension indicating means fastenedto the free end of said holt.

3. Apparatus of the kind described comprising a pair of commutatorbrushes bearing against the slip ring of a motor, a brush arm extendingfrom a pivot an equal distance to a position over each brush, a springextending between `one end of said brush arm and one of said brushes, abushing adjustably mounted in the other end of said brush arm inalignment with the second of said brushes, a base bearing against thesecond brush, said base having an axial threaded opening therein, aspring extending between said bushing and said base, the bushing beingformed with an opening whereby a bolt may be secured in the threadedopening and a tension indicating means fastened to the free end of saidbolt.

MARTIN CULKOSKY.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS `lifumber Name Date 738,747 Acly Sept. 15, 1903776,546 Priest Dec. 6, 1904 1,743,619 Pfeiier Jan. 14, 1930 1,850,742Collins Mar. 22, 1932 2,066,585 Sunnen Jan. 5, 1937 2,200,348 SummersMay 14, 1940 2,471,480 Culkosky May 3l. 1949

